The use of tinted contact lenses to alter the natural color of the iris is well known. Colorants used to produce tinted lenses generally are composed of a binding polymer and pigments. In one method of manufacturing tinted contact lenses, for examples as described and claimed in U.S. application Ser. No. 10/027,579 incorporated in its entirety herein by reference, the colorant is applied to uncured lens material, that is subsequently cured, by transfer of the colorant from a mold surface to the lens material. A disadvantage of this method for producing tinted lenses is that the lens material may not diffuse adequately into the colorant prior to cure. This results in residual, unbound polymer becoming attached to the lens surface during the hydration step of processing of the cured lens.
In order to overcome this disadvantage, it is has been attempted to increase the cure time, thus allowing for a longer period for the diffusion to take place. However, this method is problematic in that it results in an increase in edge defects due to deformation of the lens mold. Thus, a need exits for a method to improve diffusion that does not adversely affect the resulting lens.